Folding knives are common types of cutlery instruments which provide a handle for grasping a cutting implement and a sharp knife edge for cutting purposes. Folding knives have long been desirable for their inherent functionality of providing a shortened overall stored position where the blade is safely positioned inside a portion of the handle.
Lock-blade knives provide a certain amount of protection where one of a variety of locking type methods keeps the blade in the open position without (or at least limiting) the risk of having the blade close onto the fingers of the individual grasping the handle.
Fixed blade knives of course are well-known and are likely one of the earliest tools utilized by man in one form or another. Fixed blade knives have the advantage of essentially being a unitary tool with various extensions extending therefrom. Of course, various hand guards on fixed blade knives have been utilized in the prior art.
The sharp portion of a blade is potentially a liability for the handler of the instrument. Even with the most skilled blade handler, accidents can happen when the knife is utilized for any kind of cutting operation. Of course, there are various types of cutting strokes that can be engaged in when utilizing a knife. The sharp portion of a knife is often positioned against a material to be incised and a transverse downward thrust is a common stroke used to incise material. On occasion, a longitudinal motion of the knife can assist in the cutting process.
With regard to longitudinal force placed on a knife, in general, the handle of the knife is extended in the longitudinal direction (defined herein below). Given the ergonomics of the hand, the handle region generally fits along the phalanges 1-4 with the thumb wrapped therearound in a standard gripping action. Most common handles may have some contour, but by and large, any longitudinal force and in particular a longitudinal rearward force (defined further herein) is counteracted by frictional engagement between the hand of the knife handler and the surface of the handle region. Of course this frictional engagement is dependent upon the coefficient of friction of the two materials (the skin of the hand and the surface of the handle) as well as the normal force orthogonal to the various surfaces of the handle region which is dependent upon the grip of the knife handler.
These two variables can fluctuate widely when the knife is in operation in the field. For example, the coefficient of friction can alter with various materials interposed between the hand and the handle. Perspiration greatly effects the coefficient of friction, and material such as oil or perhaps certain gloves may make the knife handle more “slippery”. Further, the grip strength can vary widely. Because static friction essentially prevents any motion between the handle and the hand, the knife handler may not know the correct grip strength to keep the knife intact within his hand. Further, because kinetic friction is less than static friction, once the knife begins to slip particularly in a dynamic action such as a thrusting action described below, the hand can potentially slip forward onto the sharp portion of the knife causing considerable damage to the fingers or palm of the knife handler.
Referring back to the types of motions, a force along the longitudinal direction of the knife is often desirable to assist in incising material. Further, most knives have a pointed region with a very small surface area. This pointed region can be utilized for puncturing holes in material. However, this forward thrust is counteracted by a certain amount of resistance depending upon how easily the material is cut. Further, the knife may have a certain amount of forward velocity which de-accelerates as the hand continues to move in this forward direction. This provides an environment which is somewhat risky where if the frictional forces between the hand and handle were to fail, the hand would be thrust forward over the sharp portion of the blade seriously injuring the knife handler. In any combat situation, such an injury can seriously jeopardize an operator and the mission.
Therefore, there is a need for providing the compact nature of the folding knife and providing a system for maintaining proper hand position on the handle portion.